sustainability

Article Analyzing the Decoupling between Rural-to-Urban Migrants and Urban Land Expansion in Province,

Yaolin Liu 1,2,3, Enxiang Cai 1,* ID , Ying Jing 1, Jie Gong 1 and Zhengyu Wang 1 1 School of Resource and Environmental Science, University, 129 Luoyu Road, Wuhan 430079, China; [email protected] (Y.L.); [email protected] (Y.J.); [email protected] (J.G.); [email protected] (Z.W.) 2 Key Laboratory of Geographic Information System, Ministry of Education, Wuhan University, 129 Luoyu Road, Wuhan 430079, China 3 Collaborative Innovation Center for Geospatial Information Technology, Wuhan 430079, China * Correspondence: [email protected]; Tel.: +86-156-2309-5554

Received: 1 January 2018; Accepted: 21 January 2018; Published: 29 January 2018

Abstract: Rapid urbanization in China has caused a large number of rural-to-urban migrants (RUMs) and rapid urban land expansion (ULE). Understanding the relationship between RUMs and ULE has important implications for urban sustainable development. This study explored the spatial patterns of RUMs and ULE in Hubei Province from 2009 to 2014, and analyzed the relationship between the two using a decoupling model. The results show that: (1) a large proportion of the rural population migrated to urban areas in Hubei Province from 2009 to 2014, and the distribution of RUMs was uneven: developed areas attracted more RUMs than undeveloped regions; (2) the urban land in Hubei Province increased rapidly from 2009 to 2014, and the urban land use in Hubei Province was extensive and inefficient; (3) the decoupling types between RUMs and ULE in Hubei Province were dominated by expansive negative and weak decoupling; (4) according to the changes in per capita urban land area and decoupling types, the coordination relationship between RUMs and ULE in Hubei Province was divided into eight types, and while the relationship between RUMs and ULE in most areas were coordinated and beneficial to urban land intensive use, the rest were uncoordinated. Finally, reasonable implications for urban sustainable development and new land use policy were put forward.

Keywords: rural-to-urban migrants; urban land expansion; decoupling; coordination relationship; Hubei Province

1. Introduction Since the initiation of the “reform and opening-up” policy in 1978, China has made great achievements in social and economic development, and undergone unprecedented urbanization [1]. This urbanization has caused the phenomena of a monumental flow of rural-to-urban migration and dramatic spatial expansion in the scale of urban land in China [2,3]. Urbanization has made a significant impact on the man–land relationship between urban and rural areas in China while contributing to sustained social and economic development. The study of the change of the man–land relationship triggered by the rapid urbanization in China has emerged as a hot topic worldwide [4]. The phenomena of urban growth and population growth occur in all countries of the world, and particularly in those with industrial economies [5,6]. According to a report by the United Nations (2010), more than 50% of the world’s population nowadays lives in urban areas, and the urbanization rate will increase to 60% by 2030 [7]. The continuous migration from rural to urban areas increases the proportion of people living in towns and cities [8]. This urbanization has caused

Sustainability 2018, 10, 345; doi:10.3390/su10020345 www.mdpi.com/journal/sustainability Sustainability 2018, 10, 345 2 of 15

80% percent of the population to live in urban settlement areas in many countries across Europe [9], America, and Oceania [10]. The presence of rapid urban population growth has created difficulties for governments in relation to urban management, because it has also created a lot social and natural problems, such the depletion of land resources, man–land relationship tensions, public resource shortages, and traffic congestion [11,12]. As a result, authorities need to provide more land to increase public facilities and meet residents’ social welfare needs. The urban expansion induced by population growth has been widespread over the past decades in the United States [13], Europe [9,14], China [15], and India [16]. However, urban expansion without guiding principles is inadvisable. In other words, reasonable and effective land expansion is a crucial part of urban management, due to the presence of a floating population and residential density [17]. As an outcome of economic growth, urban land expansion (ULE) in China is proceeding at a high speed [1]. Some scholars even argued that ULE in China has outpaced urban population growth and caused inefficient urban land use [18,19]. Some of problems associated with rapid ULE include climate change [20,21], cropland loss [22], wetland destruction [23], and air and water pollution [24]. These problems lead to a reduced quality of life both in urban and rural societies [25]. On the one hand, ULE has inevitably caused a series of resource and environmental problems and cropland protection issues throughout China [26]. On the other hand, since the Chinese economy relies firmly on land inputs, local governments have quickly expanded urban land [27]. The Chinese government is trapped in the dilemma of controlling the expansion of UCL and guaranteeing the demand of economic development for urban land. In this context, studying the spatial and temporal characteristics of ULE and putting forward a reasonable plan for urban land use can be particularly important for urban sustainable development. In the process of the rapid economic growth of the past three decades, China has been experiencing rapid urbanization, as well as the largest flow of rural-to-urban migration in the history of word. While only 18% of the population lived in urban China in 1978, over 50% reside in cities today [28]. As an important driving force for urbanization and economic development, rural-to-urban migrants (RUMs) have an inextricable link with China’s ongoing urbanization process and its profound social ramifications [3]. There is a wealth of literature on China’s RUMs and urbanization. There are many studies that examine the discrimination against rural migrants and their inferior social and labor market positions [29,30]. Studies have also suggested negative health well-being consequences from rural-to-urban migration for migrants themselves [31], and to the elderly and children left behind in the rural areas [32,33]. The decision and determinants of rural-to-urban migration also concern many scholars [34,35]. Although previous research has generated an impressive body of work, most of the existing studies explore the social issues that are caused by RUMs. Despite RUMs and ULE being important characteristics of urbanization, empirical analyses of the relationship between the two have been limited. Based on the above research streams, there is a gap in the literature in studying the decoupling relationship between RUMs and ULE. In order to contribute by filling this literature gap, we take Hubei Province as a case study for quantitatively analyzing the decoupling characteristics of RUMs and ULE. Hubei Province in Central China was used as a case study due to its rapid urbanization and the obvious differences between its east and west regions. In the present study, we aimed to: (1) explore the changes in RUMs and ULE in Hubei Province from 2009 to 2014; (2) examine the types of decoupling between RUMs and ULE; and (3) classify the coordinating relationships, and bring forward targeted suggestions for sustainable urban land use.

2. Methodology

2.1. Rural-to-Urban Migrant (RUM) Estimation Model Urban population growth in China mainly comes from three areas: natural, migration, and administrative division change growths [36]. The acceleration of urbanization has made migration Sustainability 2018, 10, 345 3 of 15 growth gradually become the main reason for urban population growth [37]. The Chinese population has obvious rural-to-urban migration direction characteristics [38]. We argue that the migration population that caused urban population growth is RUMs, and the migration from urban-to-urban was not considered. The administrative divisions at the county level in Hubei Province were not adjusted from 2009 to 2014; therefore, natural and migration growth were the causes of urban population growth. After referring to relevant research and estimation methods [3], the number of RUMs can be estimated by subtracting the population of natural growth from the total population growth during the study period. The specific calculation is shown in Equation (1):

" n # Pm = Pn − P0 − P0 × ∏(1 + ri) − 1 (1) 1 where Pm is the number of RUMs, n is the number of years, Pn is the urban population in the current year, P0 is the urban population in the base year, and ri is the natural growth rate of the population in year i.

2.2. Decoupling Model A particularly useful way to examine the relationship between RUMs and ULE is by viewing it within the framework of decoupling. There are many definitions and arguments of “decoupling”, but the concept of decoupling originated in physics, and is a means of reducing or eliminating the coupling of one circuit or part from another. Carter (1966) first introduced this to the economic and environmental fields to describe the decoupling relationship between energy consumption and economic growth [39]. Subsequently, the decoupling theory became popular and widely used in the fields of energy consumption, economic, environment, etc. The Organization for Economic Co-operation and Development (OECD) (2002) initially set up the decoupling index to track environmental quality changes in its 30-member state, and formed the carbon decoupling theory [40]. Tapio (2005) improved the decoupling index to analyze the relationship between gross domestic product (GDP), traffic volumes, and CO2 emissions in the European Union (EU) [41]. Additionally, he defined eight categories of decoupling status. Romano and Zullo (2014) used a similar method to examine the relationship between land urbanization and population growth in Italy [42]. Decoupling analysis has widely applied for studying the relationship between two different systems [43,44]. In this study, the decoupling analysis was used to assess the relationship between RUMs and ULE. To ascertain the status of decoupling, we used Tapio’s model [41], which can be an expression in terms of elasticity values, as shown in Equations (2)–(4). The decoupling elasticity value α calculated by Equation (2) is the basis for determining the type of decoupling between RUMs and ULE. Equations (3) and (4) are used to measure the speed of rural-to-urban migration and urban land expansion, respectively: α = IR/ER (2)

IR = Pm/P0 (3) UA − UA ER = n 0 (4) UA0 where α is the decoupling elasticity value of RUMs and ULE, IR is the immigration rate of RUMs, ER is the expansion rate of urban land, UAn is the area of ULE in the current year, and UA0 is the area of ULE in the base year. According to the elasticity value in Equation (2), the study defines eight categories of different decoupling states (Table1). The IR (immigration rate of RUMs) and ER (expansion rate of urban land) (see Equations (3) and (4) above) can be coupled, decoupled, or negatively decoupled. In order not to over-interpret slight changes as significant, a ± 20% variation of the elasticity values around 1.0 are Sustainability 2018,, 10,, 345x FOR PEER REVIEW 4 of 14 15 and recessive coupling. In Table 1, the eight decoupling have different meanings. For example, strong still regarded as coupling here. Thus, coupling is defined as elasticity values of 0.8–1.2. On the other decoupling is indicated by a negative change rate of the RUMs indicator and a positive change rate hand, the growth of the variables can be positive or negative per se, expressed as expansive coupling of ULE growth. Other decoupling states can be explained similarly. and recessive coupling. In Table1, the eight decoupling have different meanings. For example, strong decoupling is indicated by a negative change rate of the RUMs indicator and a positive change rate of Table 1. Decoupling states between rural-to-urban migrants (RUMs) and urban land expansion ULE(ULE). growth. Other decoupling states can be explained similarly.

DecouplingTable 1. Decoupling states betweenNegative rural-to-urban Decoupling migrants (RUMs) and urbanCoupling land expansion (ULE). IR < 0, ER > 0 IR > 0, ER > 0 IR > 0, ER > 0 DecouplingStrong NegativeExpansive Decoupling negative CouplingExpansion α < 0 α > 1.2 0.8 < α < 1.2 IR < 0, ER > 0 IR > 0, ER > 0 IR > 0, ER > 0 Strong Expansive negative Expansion IR >α 0,< ER 0 > 0 IRα <> 0, 1.2 ER < 0 IR0.8 < <0,α ER< 1.2 < 0 Weak Weak negative Recession IR0> < 0, αER < 0.8> 0 IR <0 0,< αER < <0.8 0 IR0.8< < 0, αER < 1.2< 0 Weak Weak negative Recession 0 < α < 0.8 0 < α < 0.8 0.8 < α < 1.2 IR < 0, ER < 0 IR > 0, ER < 0 Recession IR < 0, ER < 0 Strong negative IR > 0, ER < 0 Recession Strong negative αα> >1.2 1.2 α α< 0< 0

3. Study Area and Data Source

3.1. Study Area Hubei Province is in the middle reaches of thethe YangtzeYangtze RiverRiver inin CentralCentral ChinaChina ((29°0529◦050′–33–33°20◦200′ N and 108108°21◦210′–116–116°07◦070′ E),E), and and has has a varyinga varying topography topography that that includes includes mountains, mountains, hills, basins,hills, basins, and plains, and coveringplains, covering an area ofan 185,900area of km185,9002. The km topography2. The topography of Hubei Provinceof Hubei isProvince west high, is west east low. high, The east west low. is aThe high-elevation west is a high-elevation mountain area, mountain and the northeastarea, and and the southeast northeast are and hilly southeast areas. The are middle hilly areas. part is The the flatmiddle Jianghan part is Plain the (alluvialflat Jianghan area ofPlain the (alluvial Riverarea of and the the Yangtze Hanjiang River River), and which the Hanjiang is an important River), foodwhich production is an important area (Figure food production1). area (Figure 1).

Figure 1. Location, administrative divisions, and elevation of Hubei Province. Figure 1. Location, administrative divisions, and elevation of Hubei Province.

As the fulcrum province of the “Rise of Central China” national strategy and the Yangtze River Economic Belt,Belt, HubeiHubei Province Province has has been been accelerating accelerating its developmentits development process, process, increasing increasing its GDP its GDP from 21.98from to21.98 2737.92 to billion2737.92 yuan, billion and yuan, increasing and itsincreasing urbanization its rateurbanization (proportion rate of urban(proportion population) of urban from 17.2%population) to 55.67% from between 17.2% to 1981 55.67% and between 2014 [45 1981]. As and shown 2014 in [45] Figure. As 2shown, the development in Figure 2, the of thedevelopment economy andof the urbanization economy and of urbanization Hubei Province of Hubei is consistent Province with is consistent that of China, with therebythat of China, making thereby this province making athis typical province subject a typical for studying subject for China. studying From China. 2009 toFrom 2014, 2009 the to area 2014, of the urban area land of urban in Hubei land Provincein Hubei increasedProvince increased from 11,638 from km 11,6382 to 12,814 km2 to km 12,8142, the km urban2, the population urban population showed showed a marked a marked increase, increase, and the and the rural population decreased. Hubei Province is in an accelerated development stage of Sustainability 2018, 10, 345 5 of 15 Sustainability 2018, 10, x FOR PEER REVIEW 5 of 14 urbanizationrural population [46] decreased., the rapid Hubeiurbanization Province will is inlead an acceleratedto continued development urban expansion stage ofand urbanization rural-to-urban [46], migration.the rapid urbanization will lead to continued urban expansion and rural-to-urban migration.

Figure 2. Changes in (a) GDP rate and urbanization rate and (b) construction land area and the urban– Figure 2. Changes in (a) GDP rate and urbanization rate and (b) construction land area and the rural population in Hubei Province. urban–rural population in Hubei Province.

3.2. Data Source 3.2. Data Source The land use data were obtained from land use and cover vector data at a 1:10,000 scale, and The land use data were obtained from land use and cover vector data at a 1:10,000 scale, derived from the Second National Land Survey (SNLS) in 2009 and the Annual Land Use Change and derived from the Second National Land Survey (SNLS) in 2009 and the Annual Land Use Change Survey (ALUCS) in 2014. The SNLS, which was conducted from 2007 to 2009, is a national systematic Survey (ALUCS) in 2014. The SNLS, which was conducted from 2007 to 2009, is a national systematic territory survey project organized by China’s State Council. The land use data obtained from the territory survey project organized by China’s State Council. The land use data obtained from the SNLS has a wide coverage and high accuracy on the basis of advanced technologies and management SNLS has a wide coverage and high accuracy on the basis of advanced technologies and management techniques. Meanwhile, the ALUCS has been running since 2010 to annually update the SNLS data techniques. Meanwhile, the ALUCS has been running since 2010 to annually update the SNLS data and collect yearly land use information. Thenceforth, a series of official, accurate, and comprehensive and collect yearly land use information. Thenceforth, a series of official, accurate, and comprehensive digital data reflecting the situation of land use in China was formed. The data of SNLS and ALUCS digital data reflecting the situation of land use in China was formed. The data of SNLS and ALUCS stand out as the most comprehensive and coherent quantifications of China’s land with legal effects stand out as the most comprehensive and coherent quantifications of China’s land with legal effects [47]. [47]. The land use classification used by SNLS and ALUCS is the Current Land Use Condition The land use classification used by SNLS and ALUCS is the Current Land Use Condition Classification Classification (GB/T21010-2007) scheme, which comprises nine one-digit categories and 23 two-digit (GB/T21010-2007) scheme, which comprises nine one-digit categories and 23 two-digit categories [48]. categories [48]. The urban land in this paper refers to urban residential land, including urban land The urban land in this paper refers to urban residential land, including urban land and town land. and town land. The socioeconomic data about GDP and population were from the statistical yearbook of Hubei The socioeconomic data about GDP and population were from the statistical yearbook of Hubei Province (2010 and 2015) and various cities in the region (2010 and 2015) [45,49]. China’s statistics Province (2010 and 2015) and various cities in the region (2010 and 2015) [45,49]. China’s statistics department did not publish data on the natural growth rate of the urban population, which was department did not publish data on the natural growth rate of the urban population, which was therefore replaced by the natural growth rate of the total population in this study. therefore replaced by the natural growth rate of the total population in this study. 4. Results 3. Results 4.1. Patterns of RUMs 3.1. Patterns of RUMs The urban population in Hubei Province increased from 26.31 million to 32.38 million from 2009 to 2014,The which urban reflects population an increase in Hubei of 6.07 Province million [increase45], of whichd from 5.44 26.31 million million were to RUMs.32.38 million The immigration from 2009 torate 2014, of total which RUMs reflects in Hubei an increase Province of was6.07 20.69%. million The[45], average of which number 5.44 million of RUMs were per RUMs. county wasThe immigration62,571. Four rate areas of in total the RUMs upper in reaches Hubei of Province the Hanjiang was 20.69%. River, namely,The average number city, of RUMs , per countyZaoyang, was and 62,571. , Four areas had in athe negative upper numberreaches of of the RUMs Hanjiang between River, 2009 namely, and 2014, Xiangyang which means city, Laohekou,that the immigrants , from and ruralDanjiang areaskou, were had less a than negative the reduction number ofof theRUMs urban between population. 2009 Theand upper2014, whichreaches means of the Hanjiangthat the Riverimmigrants are the from source rural of water area supplys were ofless the than middle the route reduction of the south-to-northof the urban Waterpopulation. Diversion The upper Project; reaches as a result of the of Hanjiang the eco-immigration River are the policy, source a largeof water number supply of localof the residents middle routemigrated of the to south-to-north other counties Water (an ecological Diversion protection Project; as policy a result in Chinaof the eco-immigration is to migrate the residentspolicy, a large who numberlive in an of ecological local residents reserve migrated to suitable to other habitats). counties (an ecological protection policy in China is to migrate the residents who live in an ecological reserve to suitable habitats). The spatial distribution of RUMs presented spatial differentiation. As shown in Figure 3, the number of RUMs in the eastern region was obviously higher than that in the west. The RUMs were Sustainability 2018, 10, 345 6 of 15

SustainabilityThe spatial 2018, 10, distribution x FOR PEER REVIEW of RUMs presented spatial differentiation. As shown in Figure6 of3 14, the number of RUMs in the eastern region was obviously higher than that in the west. The RUMs were mainly distributed in economically developed regions, such as the provincial capital Wuhan and the areas in the Jianghan plain. The immigration rate of RUMs showed an opposite spatial pattern to the RUM number.number. TheThe immigrationimmigration rate rate in in most most parts parts of of the the west west was was higher higher than than that that in in the the east. east. This This is mainlyis mainly due due to theto lowerthe lower original original urban urban population population proportion proportion in these inwestern these western regions, regions, which enables which themenables to them experience to experience faster urbanization faster urbanization development. development.

Figure 3.3.Spatial Spatial patterns patterns of RUMsof RUMs in Hubei in Hubei Province. Province. (a) RUM ( numbera) RUM (unit: number persons); (unit: (b )persons); immigration (b) rateimmigration (unit: %). rate (unit: %).

4.2.3.2. Changes in Urban Land Area The urban land in HubeiHubei ProvinceProvince expandedexpanded rapidlyrapidly from 20092009 toto 2014.2014. The total area ofof urbanurban 2 landland increasedincreased byby 1126.191126.19 kmkm22, with an increased raterate ofof 40.64%.40.64%. In the county-level units,units, thethe urbanurban landland areasareas inin all of the regions of Hubei Province have increased. Generally, Generally, economicallyeconomically developeddeveloped regionsregions showedshowed a largerlarger increasedincreased urbanurban landland area.area. The areas with a large increased urban land area werewere mainlymainly inin WuhanWuhan andand itsits vicinity.vicinity. The urban areas of certain cities (e.g., , Xiangyang, , Enshi, Xiangyang, andand )Xiaogan) alsoalso hadhad a largelarge increase (Figure4 4).). InIn contrast,contrast, thethe increasedincreased urban area of the economically backward regions inin the west was obviously lower than that of other areas. The The spatial distribution of the increased raterate of urbanurban landland areaarea waswas scattered.scattered. Unlike the increasedincreased urbanurban landland area,area, thethe increasedincreased raterate ofof urbanurban land area in the most developed areas, such as thethe countiescounties inin Wuhan,Wuhan, waswas notnot thethe highest.highest. SomeSome regionsregions in thethe middlemiddle and westernwestern parts of Hubei Province thatthat are experiencing rapid economic development showedshowed aa higher increased raterate of urban landland area.area.

Figure 4. Spatial patterns of ULE in Hubei Province. (a) Increased area;area; ((b)) increasedincreased rate.rate.

Per capita urban land area (PCULA) is an importantimportant indicator of urban land use intensity [50] [50],, and is consideredconsidered thethe nationalnational urban land useuse guidelineguideline for promotingpromoting the “construction“construction of a resource-efficientresource-efficient society”society” inin ChinaChina [[51]51].. According According to to the the Code for the ClassificationClassification ofof UrbanUrban Construction Land Use and PlanningPlanning Standards of Development Land issued by the MinistryMinistry of Housing and Urban–Rural Development in 2012 [52], the national standard of PCULA in Hubei Province is 110 m2. If PCULA exceeds the national standard, urban land use is deemed extensive and unsustainable. Sustainability 2018, 10, 345 7 of 15

Housing and Urban–Rural Development in 2012 [52], the national standard of PCULA in Hubei 2 SustainabilityProvince is 2018 110, 10 m, x .FOR If PCULAPEER REVIEW exceeds the national standard, urban land use is deemed extensive7 of 14 and unsustainable. PCULA in in Hubei Hubei Province Province increased increased from from 105.31 105.31 m m2 in2 in2009 2009 to 120 to 120 m2 in m 22014.in 2014. The urban The urban land useland in use Hubei in Hubei Province Province was extensive was extensive and inefficien and inefficient.t. Figure Figure 5 shows5 shows that PUULA that PUULA decreased decreased in most in areasmost of areas Hubei of HubeiProvince Province (62 of 87 (62 units) of 87 from units) 2009 from to 20092014, to but 2014, nearly but 2/3 nearly of the 2/3 areas of the(57 areasof 87 units) (57 of still87 units) exceeded still exceeded the national the national standard standard in 2014. in 2014.In particular, In particular, in some in some areas areas of of the the economically economically developed central and eastern regions, the urban la landnd use was extensive, an andd the the intensity intensity decreased decreased with time. These These areas areas feature feature a a flat flat terrain and favorable nature nature conditions conditions for for land land development. development. However, the speed of urban expansion was far grea greaterter than the population growth, which leads to extensive urban land use. In In the future, reasonable land management policies should be adopted to maintain the coordinated growth of urban land and population.

FigureFigure 5. 5. PerPer capita capita urban urban land land area area (PCULA) in 2014 and its changes from 2009 to 2014.

3.3.4.3. Decoupling Decoupling between between RUMs and ULE From 2009 toto 2014,2014, thethe immigration immigration rate rate in in Hubei Hubei Province Province was was 20.69%, 20.69%, and and the the UCL UCL growth growth rate ratewas 40.64%.was 40.64%. The decouplingThe decoupling was weak was decouplingweak decoup withling an with elasticity an elasticity value of value 0.51, whichof 0.51, indicates which indicatesthat the expansion that the expansion of urban landof ur wasban land faster was than faster the growththan the of growth RUMs, of and RUMs, will lead and towill inefficient lead to inefficientand extensive and urbanextensive land urban use. Asland shown use. As in shown Table2 ,in the Table proportion 2, the proportion of counties of in counties Hubei Provincein Hubei Provincebelonging belonging to each type to each during type this during period this is asperiod follows: is as expansion follows: expansion coupling (11coupling of 87 units), (11 of expansive87 units), expansivenegative decoupling negative (56decoupling of 87 units), (56 weakof 87 decoupling units), weak (16 ofdecoupling 87 units), and(16 strongof 87 decouplingunits), and (fourstrong of decoupling87 units). At (four the countyof 87 units). level, At the the speed county of level, RUMs the growth speed in of mostRUMs areas growth was in faster most than areas that was of faster ULE thanor vice that versa, of ULE while or vice the versa, speed while of RUMs the speed growth of was RUMs consistent growth withwas consistent that of ULE with only that in of a fewULE areas. only inTherefore, a few areas. it can Therefore, be concluded it can that be theconcluded relationship that the of the relationship RUMs and of ULE the inRUMs Hubei and Province ULE in didHubei not Provincereach a coordinative did not reach situation. a coordinative situation.

Table 2. Decoupling between RUMs and UCL expansion in Hubei Province.

Decoupling Types Number Sample Areas Expansive Coupling 11 Wuhan city, Yunyang, Dawu, Expansive Negative Dongxihu, Caidian, Jiangxia, Huangpi, Yangxin, Yunxi, 56 Decoupling Zhushan, Fangxian Weak Decoupling 16 Hannan, Xinzhou, , Yicheng, Xiangzhou Strong Decoupling 4 Danjiangkou, Xiangyang city, Laohekou, Zaoyang

The eastern and western regions of Hubei Province showed different decoupling patterns (Figure 6). Due to the mountainous areas in the western part of Hubei Province, the economic Sustainability 2018, 10, 345 8 of 15

Table 2. Decoupling between RUMs and UCL expansion in Hubei Province.

Decoupling Types Number Sample Areas Expansive Coupling 11 Wuhan city, Yunyang, Dawu, Yingcheng Expansive Negative Dongxihu, Caidian, Jiangxia, Huangpi, Yangxin, 56 Decoupling Yunxi, Zhushan, Fangxian Weak Decoupling 16 Hannan, Xinzhou, Daye, Yicheng, Xiangzhou Strong Decoupling 4 Danjiangkou, Xiangyang city, Laohekou, Zaoyang

SustainabilityThe eastern 2018, 10, andx FOR western PEER REVIEW regions of Hubei Province showed different decoupling patterns8 of 14 (Figure6). Due to the mountainous areas in the western part of Hubei Province, the economic development has lagged behind, andand the urbanizationurbanization levellevel waswas low.low. In recent years, the local government has vigorously promoted economic development,development, and a large proportion of the rural population has consequently migratedmigrated to cities; as a result, the urban population growth was faster than urbanurban land land growth growth in mostin most parts parts of western of wester Hubei.n Hubei. Therefore, Therefore, the western the western part of Hubeipart of Province Hubei wasProvince dominated was dominated by expansive by negativeexpansive decoupling. negative decoupling. In the eastern In part the ofeastern Hubei part Province, of Hubei the developed Province, economythe developed led to economy a strong demandled to a forstrong urban demand land and for superiorurban land land and development superior land conditions. development As a result,conditions. urban As expansion a result, hasurban been expansion fast, and has the been decoupling fast, and types the ofdecoupling many counties types in of the many east counties were weak in decouplingthe east were or weak expansive decoupling coupling. or expansive As a result coupling. of eco-environmental As a result of eco-environmental policies, the rural policies, population the migratedrural population to other migrated counties; to four other counties counties; in four the uppercounties reaches in the upper of the reaches Hanjiang of Riverthe Hanjiang had a strong River decouplinghad a strong type. decoupling type.

Figure 6. Decoupling patterns in Hubei Province from 2009 to 2014.

4.4.3.4. Coordination Relationship between RUMs and UCL PCULA cancan be be used used to to reflect reflect the coordinationthe coordinati relationshipon relationship between between RUMs RUMs and ULE, and and ULE, provide and enhancedprovide enhanced guidance guidance for urban for land urban use. land To use. make To the make decoupling the decoupling analysis analysis of RUMs of RUMs and ULE and more ULE targetedmore targeted for land for use land decision-making, use decision-making, we classified we classified the coordination the coordination relationship relationship between RUMs between and ULERUMs in and Hubei ULE Province in Hubei into Province eight categories into eight on categori the basises ofon thethe resultsbasis of of the the results decoupling of the analysis decoupling and theanalysis change and of the PCULA change (Table of PCULA3 and Figure(Table7 3). and The Figu PCULAre 7). ofThe types PCULA I, II, III,of type ands IVI, II, was III, lower and IV than was thelower national than the standard national in standard 2014; their in urban2014; their land urban use was land intensive. use was Meanwhile,intensive. Meanwhile, the PCULA the of PCULA types V, of types V, VI, VII, and VIII were higher than the national standard in 2014; their urban land use was extensive. According to the coordination relationship between RUMs and ULE, the corresponding suggestions for each were then put forward. Coordinated status: the urban land use was efficient or became increasingly intensive due to the changes in RUMs and ULE. Type I, II, V, and VI belong to this status. The RUMs growth kept pace with or exceeded the ULE growth, which led to an increasing urban land use intensity; the urban land use in this status was sustainable. The PCULA of type I and II was lower than the national standard in 2014; therefore, the approval of the quota for new urban land should be relaxed, and the supply of urban land should be given priority in the future. Meanwhile, the PCULA of type V and VI was higher than the national standard in 2014; therefore, the approval of the quota for urban land use should be restricted, and the supply of urban land should maintain the status quo to increase urban land use intensity. Uncoordinated status: the urban land use was inefficient or became increasingly extensive due to the changes of RUMs and ULE. Type III, IV, VII, and VIII belong to this status. The ULE growth Sustainability 2018, 10, 345 9 of 15

VI, VII, and VIII were higher than the national standard in 2014; their urban land use was extensive. According to the coordination relationship between RUMs and ULE, the corresponding suggestions for each were then put forward. Coordinated status: the urban land use was efficient or became increasingly intensive due to the changes in RUMs and ULE. Type I, II, V, and VI belong to this status. The RUMs growth kept pace with or exceeded the ULE growth, which led to an increasing urban land use intensity; the urban land use in this status was sustainable. The PCULA of type I and II was lower than the national standard in 2014; therefore, the approval of the quota for new urban land should be relaxed, and the supply of urban land should be given priority in the future. Meanwhile, the PCULA of type V and VI was higher than the national standard in 2014; therefore, the approval of the quota for urban land use should be restricted, and the supply of urban land should maintain the status quo to increase urban land use intensity. SustainabilityUncoordinated 2018, 10, x FOR status: PEER the REVIEW urban land use was inefficient or became increasingly extensive9 dueof 14 to the changes of RUMs and ULE. Type III, IV, VII, and VIII belong to this status. The ULE growth waswas fasterfaster thanthan thethe RUMs growth in order to reducereduce land use intensity, whichwhich makesmakes thethe urbanurban land use in this status unsustainable. Although the PCULAPCULA of type III and IV was lower than the national standard inin 2014, 2014, the the urban urban land land is developing is developing in the in direction the direction of extensive of extensive use; therefore, use; therefore, the approval the ofapproval the quota of the for quota new urban for new land urba shouldn land be should reduced be toreduced ease the to rapidease the urban rapid expansion. urban expansion. The PCULA The ofPCULA type VII of type and VIIIVII and was VIII higher was than higher the than national the national standard standard in 2014, andin 2014, there and is athere tendency is a tendency for it to continuefor it to continue to increase; to increase; therefore, therefore, the approval the approval of the quota of the for quota new construction for new construction land should land be strictlyshould restricted,be strictly andrestricted, the supply and the of newsupply urban of new land urban ought la tond be ought prohibited. to be prohibited. It is suggested It is suggested that the stock that urbanthe stock land urban ought land to be ought revitalized to be revitalized and the efficiency and the of efficiency land use improvedof land use in improved order to meet in order the demand to meet ofthe urban demand development of urban development for new urban for land. new urban land.

Figure 7. The pattern of the coordination relationshiprelationship between RUMsRUMs andand ULE.ULE.

Table 3. Coordination relationship between RUMs and ULE. S2009, per capita urban land area in 2009;

S2014, per capita urban land area in 2014; Sstan, national standard of per capita urban land area; RUMs, rural-to-urban migrants; ULE, urban land expansion.

Type Decoupling Per Capita UCL Area Number Instruction RUMs and ULE were I Expansive Coupling S2009 > S2014 S2014 < Sstan 3 coordinated, urban land use became increasingly intensive RUM growth faster than ULE, Per capita urban Expansive Negative II S2009 > S2014 S2014 < Sstan 27 urban land use became land area was lower Decoupling increasingly intensive than the national RUMs and ULE were standard, and urban III Expansive Coupling S2009 < S2014 S2014 < Sstan 4 coordinated, but urban land use land use was became extensive intensive Weak Decoupling ULE faster than RUM growth IV S2009 < S2014 S2014 < Sstan 6 and urban land use become Strong Decoupling extensive RUMs and ULE were V Expansive Coupling S2009 > S2014 S2014 > Sstan 3 coordinated, urban land use became increasingly intensive Per capita urban RUMs growth faster than UEL, land area was higher Expansive Negative VI S2009 > S2014 S2014 > Sstan 29 urban land use became than the national Decoupling increasingly intensive standard, and urban RUMs and UEL were land use was VII Expansive Coupling S2009 < S2014 S2014 > Sstan 1 coordinated, but urban land use extensive became increasingly intensive

VIII Weak Decoupling S2009 < S2014 S2014 > Sstan 14 Sustainability 2018, 10, 345 10 of 15

Table 3. Coordination relationship between RUMs and ULE. S2009, per capita urban land area in 2009; S2014, per capita urban land area in 2014; Sstan, national standard of per capita urban land area; RUMs, rural-to-urban migrants; ULE, urban land expansion.

Type Decoupling Per Capita UCL Area Number Instruction RUMs and ULE were I Expansive Coupling S2009 > S2014 S2014 < Sstan 3 coordinated, urban land use became increasingly intensive RUM growth faster than ULE, Expansive Negative Per capita urban land II S > S S < S 27 urban land use became Decoupling 2009 2014 2014 stan area was lower than the increasingly intensive national standard, and RUMs and ULE were urban land use was intensive III Expansive Coupling S2009 < S2014 S2014 < Sstan 4 coordinated, but urban land use became extensive Weak Decoupling ULE faster than RUM growth IV S2009 < S2014 S2014 < Sstan 6 and urban land use Strong Decoupling become extensive RUMs and ULE were V Expansive Coupling S2009 > S2014 S2014 > Sstan 3 coordinated, urban land use became increasingly intensive RUMs growth faster than Expansive Negative Per capita urban land VI S > S S > S 29 UEL, urban land use became Decoupling 2009 2014 2014 stan area was higher than the increasingly intensive national standard, and RUMs and UEL were urban land use coordinated, but urban land was extensive VII Expansive Coupling S < S S > S 1 2009 2014 2014 stan use became increasingly intensive Weak Decoupling UEL faster than RUMs growth VIII S2009 < S2014 S2014 > Sstan 14 and urban land use Strong Decoupling became extensive

5. Discussion

5.1. Inequality in Urban Development China has long encouraged the growth of small and medium-sized cities, and contained the growth of population in large cities [53]. The central and local governments always intended to manage city growth through planning and regulations in order to achieve equal development. However, economic development policies favor large cities. For example, large cities were granted more political power, received more investment, and enjoyed more freedom in managing local development. As a result, the economical developed large cities experienced rapid urban expansion and attracted more migration from the agricultural population [54]. Such uneven urban expansion and rural-to-urban migration intensifies the regional gaps in urban development. Our studies find that urban development in Hubei Province is highly uneven from the perspective of RUMs and ULE; the higher economic development leads to higher ULE and RUMs. For example, Wuhan city, as the most economically developed area, attracted 828927 RUMs, which accounted for more than 15% of the RUMs of Hubei Province. The urban expansion in Wuhan city was also much higher than that of other areas. Inequality has intensified globally and is now a fundamental issue in human society, especially since the recent global financial crisis. As a result, there is growing concern about spatial inequality in China as well. In China, the large cities have always had more political and economic power to enable them to gain development advantages, which intensifies the inequality of regional development. Rural populations prefer to migrate to large cities, in order to enjoy better public service and higher wages, while the large cities have sufficient labor to ensure sustained economic growth and rapid urban expansion. This phenomenon has widened the development gap between cities. The development of large cities has attracted a large number of RUMs from other regions, which has greatly plundered the development opportunities of small and medium-sized cities. Meanwhile, the large cities are faced with an increasingly severe shortage of resources and energy, and a worsening ecological environment. Urban land development is a major driving force of economic development; a more balanced urban development is critical in order to lessen regional economic Sustainability 2018, 10, 345 11 of 15 inequalities. The future economic development policies should pay more attention to the need to decentralize the land administrative power to small and medium-sized cities and equalize land use quotas across administrative units. The inequality in urban development can be gradually reduced by ensuring the urban land use in small and medium-sized cities and promoting the migration of the agricultural population to small and medium-sized cities.

5.2. Implications for New Land Use Policy As a result of urbanization, many rural people have poured into cities seeking higher income, better living standards, and more job opportunities [3]. However, this migration has caused a land dilemma between urban and rural areas [55]. The increasing urban population requires more construction land in order to provide living space and to develop industries; at the same time, many houses and extensive construction land in rural areas are left unused (known as “hollowed villages”). The Chinese government has conducted an initiative land reform—the “the increasing versus decreasing balance” land use policy, which is known in Chinese as zeng jian gua gou (ZJGG)—in an attempt to get out of the dilemma in which the cities have great demand for construction land, while the villages have considerable unused and enclosed construction land [56]. This policy was developed to connect the increase in urban construction land with the decrease in rural construction land, and achieve equilibrium in the total supply of construction land [57]. The ZJGG policy promotes the integration of urban–rural development and the protection of farmland, and provides a solution to the land demand for urban development [58]. Although the ZJGG policy can help cities obtain land-use indicators, it does not pay enough attention to the problem of urban land shortage due to rapid population growth [59]. In order to solve the problem of the inconsistency of population urbanization and land urbanization in the process of urban development, a new land use policy of “population land hook”, which has the Chinese name ren di gua gou (RDGG), was piloted in Province with satisfactory effect and popularized nationwide in 2016. The RDGG policy is the extension of the former land policy of ZJGG, and states that the scale of ULE should be coordinated with the size of RUMs, and that the annual quota of new construction land for a city is determined by the number of attracted RUMs [60]. Restraining urban rapid growth and prioritizing the rational planning of urban land use are tasks that urban managers face in many developing countries [61]. In China, the management of the allocation of new urban land indicators was through general land planning, with a “top–down” planning mode [62]. The allocation of new urban land indicators in this planning mode is greatly affected by the local economic and administrative factors, while ignoring the human-oriented land demand. The new land use policy of RDGG aims to improve urban land use efficiency by planning control, optimizing land arrangements, and strictly implementing national PCULA standards. This policy focuses on the coordination between the RUMs and ULE. Analyzing the decoupling relationship between RUMs and ULE could serve as a useful reference for the implementation of the RDGG, and help implement targeted dynamic allocation measures of new urban land indicators according to different coordination relationships between RUMs and ULE.

5.3. Recommendations for Future Study This study explored the spatial pattern of RUMs and ULE in Hubei Province from 2009 to 2014, and analyzed the decoupling relationship between RUMs and UCL. However, there are some improvements that could be made in future studies. First, the decoupling relationship between RUMs and ULE may present different patterns in different temporal dimensions; further study should add more time series data to reflect the dynamic relationship. Second, the monumental flow of RUMs in rapid urbanization also restructures the rural land pattern; the interactions between rural and urban land caused by RUMs should be explored in the further study. Sustainability 2018, 10, 345 12 of 15

6. Conclusions As a developing country, China’s economic development will inevitably lead to urban expansion at the expense of cropland. At the same time, China has to maintain a sufficient amount of cropland to feed the world’s largest population. Therefore, the land available for urban development is become increasingly scarce and valuable. It is of great significance for urban sustainable development to reasonably arrange the new urban land use indicators by analyzing the decoupling relationship between RUMs and ULE. This paper explored the changes of RUMs and ULE, and quantitatively analyzed the decoupling relationship between the two. The results of this study could provide valuable information for the implementation of the new land use policy (e.g., RDGG), and the sustainability of urban development. The research results are concluded as below: (1) A large number of people migrated from rural to urban areas in Hubei Province from 2009 to 2014, and the uneven spatial distribution of RUMs was characterized by more RUMs being attracted to developed areas than to undeveloped areas; (2) The urban land area in Hubei Province increased rapidly, especially the economically developed regions, and the urban land use in Hubei Province was extensive and inefficient; (3) The decoupling types between RUMs and ULE in Hubei Province were dominated by expansive negative and weak decoupling. The western part of Hubei Province was dominated by expansive negative decoupling, whereas the decoupling types of many units in the east were weak decoupling or expansive coupling; (4) On the basis of the results of a decoupling analysis and changes in the PCULA, the coordination relationship between RUMs and ULE in Hubei Province was classified into eight categories; the relationship between RUMs and ULE in most areas were coordinated and beneficial to the intensive use of urban land, while the rest were uncoordinated.

Acknowledgments: This work was financially supported by the National Key Research and Development Program (Grant No.: 2017YFB0503505) and National Natural Science Foundation (No.: 41771432). Author Contributions: Yaolin Liu and Enxiang Cai conceived and designed the experiment; Ying Jing and Jie Gong helped the data analysis; Ying Jing and Zhengyu Wang helped the language correction; Yaolin Liu and Enxiang Cai wrote the paper. Conflicts of Interest: The authors declare no conflict of interest.

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